A motor control center (MCC) is an electrical cabinet dedicated to motor control. A motor control unit is generally a drawer-like container of electrical components, such as circuit breakers, motor starters, and pilot devices, which slides into a front section of an MCC and connects to a common power bus running vertically along the back side or back section of the MCC.
In order to provide access for pilot device signals and test signals, the motor control unit generally includes a feed-through connector mounted through a side wall of its enclosure. The control signals may include, for example, low voltage signals for pilot lights, push buttons, selector switches, or other control devices. The test signals may include, for example, low voltage signals for diagnostic maintenance, from internal test points.